photoelectric adj : of or pertaining to photoelectricity; "the photoelectric effect" [syn: photoelectrical]

English

Adjective

1. Of, or relating to the electric effects of electromagnetic radiation

Translations

• Italian: fotoelettrico

Derived terms

• photoelectric absorption
• photoelectric cell
• photoelectric colorimeter
• photoelectric constant
• photoelectric control
• photoelectric counter
• photoelectric densitometer
• photoelectric detector
• photoelectric device
• photoelectric door opener
• photoelectric effect
• photoelectric fluoometer
• photoelectric imaging
• photoelectric intrusion detector
• photoelectric lighting control
• photoelectric magnitude
• photoelectric photometer
• photoelectric photometry
• photoelectric plethysmograph
• photoelectric process
• photoelectric pyrometer
• photoelectric reader
• photoelectric reflectometer
• photoelectric relay
• photoelectric scanner
• photoelectric sorter
• photoelectric transmissometer
• photoelectric tube
• photoelectric turbidimeter

Related terms

• photoelectricity

The photoelectric effect is a quantum electronic phenomenon in which electrons are emitted from matter after the absorption of energy from electromagnetic radiation such as x-rays or visible light. The emitted electrons can be referred to as photoelectrons in this context. The effect is also termed the Hertz Effect, due to its discovery by Heinrich Rudolf Hertz, although the term has generally fallen out of use.

Study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave–particle duality.

1. Inner photoelectric effect (see photodiode below). The hole left behind can give rise to auger effect, which is visible even when the electron does not leave the material. In molecular solids photons are excited in this step and may be visible as lines in the final electron energy. The inner photoeffect has to be dipole allowed. The transition rules for atoms translate via the tight-binding model onto the crystal. They are similar in geometry to plasma oscillations in that they have to be transversal.
2. Ballistic transport of half of the electrons to the surface. Some electrons are scattered.
3. Electrons escape from the material at the surface.

In the three-step model, an electron can take multiple paths through these three steps. All paths can interfere in the sense of the path integral formulation. For surface states and molecules the three-step model does still make some sense as even most atoms have multiple electrons which can scatter the one electron leaving.

History

Early observations

In 1839, Alexandre Edmond Becquerel observed the photoelectric effect via an electrode in a conductive solution exposed to light. In 1873, Willoughby Smith found that selenium is photoconductive.

Hertz's spark gaps

In 1887, Heinrich Hertz observed the photoelectric effect and the production and reception of electromagnetic (EM) waves. He published these observations in the journal Annalen der Physik. His receiver consisted of a coil with a spark gap, where a spark would be seen upon detection of EM waves. He placed the apparatus in a darkened box to see the spark better. However, he noticed that the maximum spark length was reduced when in the box. A glass panel placed between the source of EM waves and the receiver absorbed ultraviolet radiation that assisted the electrons in jumping across the gap. When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as quartz does not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained. He did not further pursue investigation of this effect, nor did he make any attempt at explaining how this phenomenon was brought about.

JJ Thomson: electrons

In 1899, J. J. Thomson investigated ultraviolet light in Crookes tubes. Influenced by the work of James Clerk Maxwell, Thomson deduced that cathode rays consisted of negatively charged particles, later called electrons, which he called "corpuscles". In the research, Thomson enclosed a metal plate (a cathode) in a vacuum tube, and exposed it to high frequency radiation. It was thought that the oscillating electromagnetic fields caused the atoms' field to resonate and, after reaching a certain amplitude, caused a subatomic "corpuscle" to be emitted, and current to be detected. The amount of this current varied with the intensity and color of the radiation. Larger radiation intensity or frequency would produce more current.

Radiant energy

• Photomultiplier
• Solar cell
• Solar power
• Transducer

Physics:

• Atom
• Corona discharge
• Double-slit experiment
• Electron
• Gamma ray
• Nobel Prize in Physics
• Optical phenomenon
• Photoelectron spectroscopy
• Photon
• Photon dynamics in the double-slit experiment
• Photon polarization
• Planck's law of black body radiation
• Quantum mechanics
• Radiant energy
• Wave-particle duality

People:

• Aleksandr Grigorievich Stoletov
• Albert Einstein
• Heinrich Hertz
• Ernest Lawrence
• Robert Millikan
• Max Planck
• J. J. Thomson

Lists:

• List of electronics topics
• List of optical topics
• List of physics topics
• Timeline of solar cells
• Scientific method list
• Timeline of mechanics and physics

External links

• Nave, R., "Wave-Particle Duality". HyperPhysics.
• "Photoelectric effect". Physics 2000. University of Colorado, Boulder, Colorado.
• ACEPT W3 Group, "The Photoelectric Effect". Department of Physics and Astronomy, Arizona State University, Tempe, AZ.
• Haberkern, Thomas, and N Deepak "Grains of Mystique: Quantum Physics for the Layman". Einstein Demystifies Photoelectric Effect, Chapter 3.
• Department of Physics, "The Photoelectric effect". Physics 320 Laboratory, Davidson College, Davidson.
• Fowler, Michael, "The Photoelectric Effect". Physics 252, University of Virginia.

Applets

• Curull, Xavi Espinal, "Photoelectric effect Applet". (Java)
• Fendt, Walter, and Taha Mzoughi, "The Photoelectric Effect". (Java)
• "Applet: Photo Effect". Open Source Distributed Learning Content Management and Assessment System. (Java)
• "Photoelectric Effect". The Physics Education Technology (PhET) project. (Java)

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